The sugar glucose is essential to the protozoan parasite Trypanosoma brucei, the causative agent of African sleeping sickness. Heretofore, we have known very little about the regulation of a key enzyme in glucose metabolism, hexokinase (TbHK1). Recently, our group has identified a second HK (TbHK2) that regulates the first. This observation, along with our finding that products from other cellular processes can alter HK activity, suggest that HK serves as a central mediator of metabolism in the cell. Here, we propose to explore how TbHK2 regulates TbHK1 at both the mRNA and protein levels. Further, we will consider how the enzyme is regulated by other mechanisms, including phosphorylation and inhibition by other cellular metbolites. Our long-term goal is to carefully characterize the roles of the two HKs in the biology of T. brucei, with a particular emphasis on understanding the role of these proteins in regulation of metabolism. We hypothesize that the proteins may regulate the cells'response to environmental changes in nutrient availability that occurs as the parasites move from one host to another. PUBLIC HEALTH RELEVANCE: Trypanosoma brucei, the causative agent of African sleeping sickness, infects an estimated 500,000 people annually and is fatal if untreated. The research proposed here will further our understanding of the regulation of a metabolic pathway that is essential to the parasite suggesting that we may identify novel therapeutic targets.